There is considerable interest in signal transduction mechanisms underlying neuroplasticity and the mechanisms for regulating the expression of specific regulatory proteins important for these processes in neurons. The purpose of the proposed studies is to test the following hypotheses: 1) expression of the type I Ca2+/calmodulin sensitive adenylyl cyclase may be controlled, at least in part, by a neurospecific promoter and/or enhancer that limits its expression to subclasses of neurons in the central nervous system and 2) type I calmodulin-sensitive adenylyl cyclase plays an important role for basic signalling mechanisms in the molecular basis of learning and memory. To test these hypotheses Dr. Villacres plans to accomplish the following objectives: 1) Isolate and characterize the 5' upstream DNA sequence for the type I adenylyl cyclase using mouse genomic clones for the type I adenylyl cyclase in order to define its promoter and enhancer elements, 2) synthesize constructs comprised of type I adenylyl cyclase DNA fragments fused to a reporter gene in order to characterize the promoter, 3) generate transgenic mice expressing beta-galactosidase under the control of the type I adenylyl cyclase promoter, and 4) disrupt the type I adenylate cyclase gene in ES cells using the positive-negative selection method. A targeting vector from the genomic clone will be constructed that can be used to disrupt the gene for the type I adenylate cyclase in ES cells. If successful, these cells will be used to develop mice deficient in this enzyme. The availability of specific promoters for subclasses of neurons involved in learning and memory may be a powerful tool for studying these functions in neurons. Furthermore, the disruption of the type I adenylyl cyclase gene in transgenic mice by homologous recombination may provide a better understanding of the role of this enzyme in specific areas of the brain.